Various jolt limiting methods and systems are disclosed in the cross referenced applications and patents. German disclosure document DT-OS No. 21 24.204 (corresponding to U.S. Application Ser. No. 252,559 filed May 12, 1972; now U.S. Pat. No. 3,942,393) discloses apparatus in which the friction elements which control the transmission of torque between the engine and the transmission output are regulated to a prescribed rate of change of engine speed with respect to time. This prescribed rate of change of engine speed is computed as a function of engine speed, engine torque, the direction of the gear shift, the selected gear ratio, the temperature of the oil in the transmission and the load of the motor vehicle. The so computed desired jolt value and the actual jolt as computed by the rate of change of engine speed with respect to time are applied to a regulator which in turn, through an amplifier and an output control, controls the pressure regulator for the friction elements of the transmission. The peaks which appear in the variation with respect to time of the torque and of the oil pressure in the pressure regulator during the gear shift are decreased by means of a delay element, for example an RC circuit, or by oil nozzles in the pressure system.
It is a disadvantage of these known systems that the actual jolt is only partially represented, while the jolt which exists after the friction elements have become completely engaged, that is the jolt resulting from the rigidity of the transmission output, is not taken into consideration at all.
A system has further been disclosed (U.S. Pat. No. 4,172,505) in which the then-present value of the jolt is determined, the maximum value of the jolt if complete engagement of the friction elements were to take place at the particular time is computed, the higher of the two values is compared to the maximum permissible value of jolt, and the difference between these two signals is applied to a regulator for activating the friction elements.